SIMMER code

More detailed investigations are necessary, also performing mechanistic analyses starting from the initiation of the accident and following the whole melt progression up to final neutronic shutdown in the core. The SIMMER-III code will be used when the implementation of an advanced neutronics module is finished. 

Regarding the SIMMER III code, being developed by PNC (Japan), the Europeans (CEA, FZKA) are participating in the qualification of the code. 

Important work has been made on this important phase of HCDA with the SIMMER II code and the "Advanced Fluid Dynamics Model" (AFDM code). 

Codes have been developed (PHYSURA-GRAPPE, SURPASS), others have used the SCARABEE-N tests as contribution to the validation (SIMMER II, SABRE) and much interesting information for other accident situations was made available, especially for the transition phase. 

Following a better understanding of the SIMMER II and Advanced Fluid Dynamics Model (AFDM) codes, the European have dedded to join the PNC (Japan) to developed SIMMER III. PNC is the code developper. 

Within the SIMMER-III cooperation between PNC and the European partners FZK, the Forschungszentrum Karlsruhe (FZK) is contributing both in the code development and the code assessment. The main contributions to these items are ... 

The CDA analysis code development and validation studies have continued extensively SAS4A for CDA s initiating phase and SIMMER-III for the transition phase. For SAS4A, tmder collaboration with KfK and CEA, a reference code version REF-94 has been developed for common use in the future. A special single channel code PAPAS-2S, which models detailed fuel pin mechanics, is also being elaborated through CABRI analyses. The fluid-dynamics system in SIMMER-III has approached its completion /and the coupling with the neutronics is underway. A code assessment... 

Reasonable agreement has been reached between experimental results and calculations with the SIMMER II code [5.18], In particular, the formation of a closed cavity and the thermal equilibrium reached about 22 sec after the initiation of the transient correspond to the experimental observation in the case of MOL 7 C/5. Similar calculations are planned with the code SURPASS [5.15],... 

Analysis of the MOL 7C Experiments with the SIMMER II Code. Proceedings of the 14th Meeting of the Liquid Metal Boiling Working Group - Brasimone/Italy, 16-18 April, 1991. 

Yamano, H., Fujita, S., Tobita, Y., Sato, I., Niwa, H., 2008. Development of a three dimensional CDA analysis code SIMMER-IV and its first application to reactor case. Nuclear Engineering and Design 238 (1), 66—73. 

CEA is also continuing validation work for the re-criticality risk analysis code SIMMER m. An important aspect of this research is the analysis of the molten and boiling mixed pool behaviour of taking into account the CABRI/Raft ball-trap experiments. 

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